How is the range of a set of data different from the iqr ?

Norma has an a-frame cabin. the back is shown below. how many square feet of paint will she need to cover the back of the cabin? explain how you found the answer.

Evaluate the expression. (9 + 5)(3 + 2)0

An automobile assembly line operation has a scheduled mean completion time, μ, of 12 minutes. the standard deviation of completion times is 1.6 minutes. it is claimed that, under new management, the mean completion time has decreased. to test this claim, a random sample of 33 completion times under new management was taken. the sample had a mean of 11.2 minutes. assume that the population is normally distributed. can we support, at the 0.05 level of significance, the claim that the mean completion time has decreased under new management? assume that the standard deviation of completion times has not changed.